update README

README.md

@@ -1,15 +1,17 @@
 # Data for Freifunk Map, Graph and Node List
 
 ffmap-backend gathers information on the batman network by invoking 
-   batctl
+
-and
+ * batctl,
-   batadv-vis
+ * alfred-json and
+ * batadv-vis
+
 as root (via sudo) and has this information placed into a target directory
 as the file "nodes.json" and also updates the directory "nodes" with graphical
 representations of uptimes and the number of clients connecting.
 
-The target directory is suggested to host all information for interpreting those
+Run `backend.py --help` for a quick overview of all available options.
-node descriptions, e.g. as provided by https://github.com/ffnord/ffmap-d3.git .
+
 When executed without root privileges, we suggest to grant sudo permissions
 within wrappers of those binaries, so no further changes are required in other
 scripts:
@@ -24,30 +26,35 @@ EOCAT
 and analogously for batadv-vis. The entry for /etc/sudoers could be
 whateveruser   ALL=(ALL:ALL) NOPASSWD: /usr/sbin/batctl,/usr/sbin/batadv-vis,/usr/sbin/alfred-json
 
-The destination directory can be made directly available through apache:
-<pre>
-$ cat /etc/apache2/site-enabled/000-default
-...
-        <Directory /home/whateverusername/www/>
-                Options Indexes FollowSymLinks MultiViews
-                AllowOverride None
-                Order allow,deny
-                allow from all
-        </Directory>
-...
-
-$ cat /etc/apache2/conf.d/freifunk
-Alias /map /home/ffmap/www/
-Alias /firmware /home/freifunk/autoupdates/
-</pre>
-
-To execute, run 
- ./mkmap.sh ../www
-The script expects above described sudo-wrappers in the $HOME directory of the user executing
-the script. If those are not available, an error will occurr if not executed as root. Also,
-the tool realpath optionally allows to execute the script from anywhere in the directory tree.
-
 For the script's regular execution add the following to the crontab:
 <pre>
-*/5 * * * * /home/ffmap/ffmap-backend/mkmap.sh /home/ffmap/www
+* * * * * /path/to/ffmap-backend/backend.py -d /path/to/output -a /path/to/aliases.json --vpn ae:7f:58:7d:6c:2a --vpn d2:d0:93:63:f7:da
 </pre>
+
+# Data format
+
+## nodes.json
+
+    { 'nodes': {
+        node_id: { 'flags': { flags },
+                   'firstseen': isoformat,
+                   'lastseen': isoformat,
+                   'nodeinfo': {...},         # copied from alfred type 158
+                   'statistics': {
+                      'uptime': double,       # seconds
+                      'memory_usage': double, # 0..1
+                      'clients': double,
+                      'rootfs_usage': double, # 0..1
+                      'loadavg': double,
+                      'gateway': mac
+                    }
+                 },
+        ...
+      }
+      'timestamp': isoformat
+    }
+
+### flags (bool)
+
+- online
+- gateway